短繊維強化ナイロン66 CFRPの破壊機構とAE特性

抄録

In this paper, the fracture mechanism and AE behavior of a short carbon fiber reinforced nylon 66 composite with a center crack through the thickness during monotonous tensile deformation are studied. It is shown that most of AE signals occur in the region of stable crack propagation and there is an obvious increase in AE activity at the initial stable cracking. The dimple patterns can be observed in SEM for all of materials and the AE characteristics of them are clarified. It is also shown that a proportional relation between J integral and COD holds well for the composites, but the proportional coefficient reduces as the fiber content or the ratio of crack length to specimen width increases. Using AE energy aspect ratio, which is defined as the ratio of the cumulative AE energy to the one at the initial stable crack, an exponent relationship between AE energy aspect ratio and J integral can be obtained experimentally. The value of the exponent m in the above relation is roughly the same during stable crack propagating even if the fiber content or the ratio of crack length to specimen width varies.